Have you ever come across a Windows computer where the mouse is missing, or not functioning. This can make it extremely difficult to control the computer, even if you use keyboard shortcuts there are things that still require a mouse.
There is a feature in XP called MouseKeys which is part of the accessibility utilities. This program enables you to use the numbers on the keypad to control the mouse pointer. To activate the MouseKeys functionality, press CTRL + left SHIFT + NUM LOCK keys all at the same time.